SERVER-22913 create SyncSourceResolver to move connectToSyncSource out of the oplogreader

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• Closed

SERVER-26342 Incorrect and misleading log message when blacklisting sync source because we are too stale

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• Closed

SERVER-25145 During rollback (or w/minvalid invalid) select sync source based on end OpTime

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• Closed

SERVER-26415 Make sure to catch up to minValid before exiting rollback

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• Closed